Architectural lighting fixtures for retail stores, hotel lobbies, and the like, have been designed for placement along the upper edge of a wall at the juncture of the wall and ceiling for providing a "washing" light effect downwardly from the fixture along the vertical wall surface. For the most desirable results, the brightness or intensity of the light emanating from the fixture along the wall should be uniform along the entire length of the wall and, to the extent possible, from top to bottom.
Uniformity of wall-wash lighting fixtures along the wall length has been difficult to achieve. Primarily this is because of the fact that the bulbs which are used generally are fluorescent bulbs of four foot length (a readily available commercial, standard length). Consequently, a number of fixtures needs to be placed end-to-end to provide illumination of an entire wall surface. At the junctures of the fixtures, there generally is a darker area. Also, fluorescent bulbs emit less light near their ends than at the center. As a consequence, most "wall-wash" lighting fixtures produce a somewhat uneven distribution of light along the wall, creating a type of "scalloped" effect of brighter and darker regions. This is most noticeable directly beneath the fixture itself.
It also has been a problem with prior art lighting fixtures for producing the "wall-wash" effect, that the light intensity rapidly becomes less a short distance down the wall. Part of this is due to the fact that, for aesthetic purposes, the fixtures must be mounted as close as possible to the juncture of the wall and the ceiling; and reflection of light from the fixture to the mid-point and lower points of the wall has been difficult to achieve.
Standard wall-wash fixtures employ a generally shallow rectangular housing which has an elongated rectangular opening along the wall and slightly off-set from the center of the housing. The bulb tupically is located above the edge of the opening which is farthest from the wall, and a uniform curved elongated reflector section is placed behind the bulb. Such a reflector section usually is in the form of a continuous compound curve. The "scalloped" lighting effect, mentioned above, is a result of such reflector which has been tolerated in the past.
Other approaches to providing a uniform illumination of a planar surface, such as a wall or ceiling, have been made. One such approach is disclosed in the patent to Molnar, U.S. Pat. No. 4,349,866. This patent discloses an indirect lighting fixture utilizing an HID bulb in combination with a reflector having combined curved and flat reflector sections throughout its length. This fixture is designed to obtain a uniform illumination of a ceiling, but it is capable of only a relatively narrow band of illumination and does not provide any suggestion as to how an entire wall surface, or ceiling surface, can be evenly and uniformly illuminated.
A lighting fixture which is used to direct light to a location off-set from the fixture, is disclosed in U.S. Pat. No. 4,383,289 to Lewin. This fixture employs a U-shaped floursecent bulb of a relatively short length and a specialized reflector to illuminate a work area located below and off to one side of the fixture. The fixture reflector is a uniform compound curved cross-section reflector of a type somewhat similar to those used in the prior art wall-wash reflectors discussed above.
Other attempts to obtain specialized light patterns or spread of light from a fixture by use of non-uniform reflector sections, are disclosed in the patents to Welty, No. 3,382,357 and Erikson, No. 1,779,591. The Welty patent discloses a street lighting luminaire, which has a number of scalloped, longitudinally extending panels, located above the bulb, to reflect the light to corresponding opposite panel sections, and then in a double reflection out from the fixture to spread the light. The double reflection, of course, significantly reduces the efficiency of the fixture. In addition, the object of this fixture is to produce a pre-established pattern of light on the ground beneath the fixture and it is not intended for illuminating a wall surface which is perpendicular to the surface on which the fixture is mounted.
The Erikson patent is for a showcase reflector and has uniform reflector sections located behind the bulb, extending along its length. No compensation for non-uniform light intensity from the bulb is made.
A patent which is directed to a fixture for illuminating a vertical wall surface from above, is U.S. Pat. No. 3,643,089 to Marantz. The fixture disclosed in this patent, however, is not an elongated wall-wash fixture, but instead, is a complex multiple reflector fixture employing multiple reflections from a generally point-light source to achieve the illumination desired. As a result, the Marantz fixture inherently is limited to walls of relatively short lengths and could not be used to provide anything approaching uniform illumination of a wall of even more than a few feet in length.
It is desirable to provide a wall-wash lighting fixture which overcomes the disadvantages of the prior art mentioned above. It also is desirable to provide such a fixture with the capability of overcoming these disadvantages with minimum departure from the housing configurations presently used for wall-wash lighting fixtures. It further is desirable to provide a wall-wash lighting fixture which is simple to manufacture.